By the close of 1882, the inhabitants of the American West had earned their reputation as untamed and dangerous. The line between heroes and villains is narrow and indistinct. The concept that a man may only kill if backed into a corner is antiquated. Lives are worth less than horses. Treasures are worth killing for. And the law is written in the blood of those who came before. The only men staving off total chaos are the few who take the letter of the law at its word and risk their lives to uphold it. But in the West, the rules aren't always played according to Hoyle.

US Marshals Eli Flynn and William Henry Washington are escorting two prisoners to New Orleans for trial when they discover there's more to the infamous shootist Dusty Rose and the enigmatic man known only as Cage than merely being outlaws. When forces beyond the marshals' control converge on the paddlewheeler they have hired to take them downriver, they must choose between two dangers: playing by the rules at any cost or trusting the very men they are meant to bring to justice.